Now showing items 41-60 of 58330

    • Origin of active sites on silica-magnesia catalysts and control of reactive environment in the one-step ethanol-to-butadiene process

      Chung, Sang-Ho; Li, Teng; Shoinkhorova, Tuiana; Ramirez, Adrian; Mukhambetov, Ildar; Abou-Hamad, Edy; Shterk, Genrikh; Telalovic, Selvedin; Dikhtiarenko, Alla; Sirks, Bart; Lavrik, Polina; Tang, Xinqi; Weckhuysen, Bert M.; Bruijnincx, Pieter; Gascon, Jorge; Ruiz-Martinez, Javier (Research Square Platform LLC, 2022-05-18) [Preprint]
      Wet-kneaded silica–magnesia is a benchmark catalyst for the one–step ethanol-to-butadiene Lebedev process. Magnesium silicates, formed during wet-kneading, have been proposed as active sites responsible for butadiene formation, and their catalytic performance has been mainly explained by the variations in the ratio of acid and base sites. While the Lebedev process was developed in the 1930s, However, a detailed insight into how the peculiar, yet essential wet-kneading synthesis leads to the generation, location, and catalytic role of magnesium silicates has not been fully established. Here, we demonstrate that magnesium silicates formation occurs via dissolution of Si and Mg subunits from SiO2 and Mg(OH)2 precursors, initiated by the alkaline pH of the aqueous wet-kneading medium, followed by cross-deposition of the dissolved species on the precursor surfaces. Building on these new insights, two individual model systems (Mg/SiO2 and Si/MgO) were synthesized, representative of the constituents of the wet-kneaded silica–magnesia catalyst, by selective dissolution/deposition induced by pH alteration of the aqueous wet-kneading medium. Using these model catalysts, we demonstrate that the location of the magnesium silicates (i.e., Mg on SiO2 or Si on MgO) governs not only their chemical nature but also the ethanol adsorption configuration, which ultimately cause the catalyst material to be selective mainly for ethylene or butadiene. We demonstrate close proximity at the particle level of the of acid and basic sites is a prerequisite to promote the butadiene formation. The insights gained from the new structure–performance relationships that correlate catalytic activity with types and nature of magnesium silicates can offer new possibilities for the development of next generation Lebedev catalysts.
    • Continuous extraction and concentration of secreted metabolites from engineered microbes using membrane technology

      Overmans, Sebastian; Ignacz, Gergo; Beke, Aron K.; Xu, Jiajie; Saikaly, Pascal; Szekely, Gyorgy; Lauersen, Kyle J. (Green Chemistry, Royal Society of Chemistry (RSC), 2022-05-18) [Article]
      Microalgal cultivation in photobioreactors and membrane separations are both considered sustainable processes. Here we explore their synergistic combination to extract and concentrate a heterologous sesquiterpenoid produced by engineered green algal cells. A hydrophobic hollow-fiber membrane contactor was used to allow interaction of culture broth and cells with a dodecane solvent phase to accumulate algal produced patchoulol. Subsequent continuous membrane extraction of patchoulol from dodecane enabled product concentration in a methanol stream as well as dodecane recovery for its reuse. A structure-based prediction using machine learning was used to model a process whereby 100% patchoulol recovery from dodecane could be achieved with solvent-resistant nanofiltration membranes. Solvent consumption, E-factor, and economic sustainability were assessed and compared with existing patchoulol production processes. Our extraction and product purification process offers six- and two-orders of magnitude lower solvent consumption compared to synthetic production and thermal-based separation, respectively. Our proposed methodology is transferable to other microbial systems for the isolation of high-value isoprenoid and hydrocarbon products.
    • Improving HfO 2-Based Resistive Switching Devices by Inserting a TaO x Thin Film via Engineered In Situ Oxidation

      Wang, Tao; Brivio, Stefano; Cianci, Elena; Wiemer, Claudia; Perego, Michele; Spiga, Sabina; Lanza, Mario (ACS Applied Materials & Interfaces, American Chemical Society (ACS), 2022-05-18) [Article]
      Resistive switching (RS) devices with binary and analogue operation are expected to play a key role in the hardware implementation of artificial neural networks. However, state of the art RS devices based on binary oxides (e.g., HfO2) still do not exhibit enough competitive performance. In particular, variability and yield still need to be improved to fit industrial requirements. In this study, we fabricate RS devices based on a TaOx/HfO2 bilayer stack, using a novel methodology that consists of the in situ oxidation of a Ta film inside the atomic layer deposition (ALD) chamber in which the HfO2 film is deposited. By means of X-ray reflectivity (XRR) and time-of-flight secondary ion mass spectrometry (ToF-SIMS), we realized that the TaOx film shows a substoichiometric structure, and that the TaOx/HfO2 bilayer stack holds a well-layered structure. An exhaustive electrical characterization of the TaOx/HfO2-based RS devices shows improved switching performance compared to the single-layer HfO2 counterparts. The main advantages are higher forming yield, self-compliant switching, lower switching variability, enhanced reliability, and better synaptic plasticity.
    • Variance partitioning in spatio-temporal disease mapping models

      Franco-Villoria, Maria; Ventrucci, Massimo; Rue, Haavard (Statistical methods in medical research, SAGE Publications, 2022-05-18) [Article]
      Bayesian disease mapping, yet if undeniably useful to describe variation in risk over time and space, comes with the hurdle of prior elicitation on hard-to-interpret random effect precision parameters. We introduce a reparametrized version of the popular spatio-temporal interaction models, based on Kronecker product intrinsic Gaussian Markov random fields, that we name the variance partitioning model. The variance partitioning model includes a mixing parameter that balances the contribution of the main and interaction effects to the total (generalized) variance and enhances interpretability. The use of a penalized complexity prior on the mixing parameter aids in coding prior information in an intuitive way. We illustrate the advantages of the variance partitioning model using two case studies.
    • Soft perovskites stabilized by robust heterojunctions

      Wu, Zhifang; Alsalloum, Abdullah; Mohammed, Omar F.; Bakr, Osman (Joule, Elsevier BV, 2022-05-18) [Article]
      Rapid progress has recently been made in the development of perovskite solar cells (PSCs) with power conversion efficiencies (PCEs) that are now comparable with those of crystalline Si, the traditional and well-established solar cell technology. Recently in Science, Fang and co-workers reported a PSC in an inverted configuration with a high efficiency of >24% (23.5% certified) and remarkable operational stability. In this work, robust heterojunctions were constructed at the interface to suppress ion migration and favorably adjust the interfacial energy band alignment, addressing two major issues associated with the poor PCEs and stability of inverted PSCs.
    • ω-FWI: Robust full-waveform inversion with Fourier-based metric

      Izzatullah, Muhammad; Alkhalifah, Tariq Ali (arXiv, 2022-05-18) [Preprint]
      Full-waveform inversion is a cutting-edge methodology for recovering high-resolution subsurface models. However, one of the main conventional full-waveform optimization problems challenges is cycle-skipping, usually leading us to an inaccurate local minimum model. A highly investigated track to alleviate this challenge involves designing a more global measure of misfit between the observed and modelled data beyond the sample-to-sample comparison. However, most of these approaches admit relatively smooth inversion results. Here, we introduce a novel misfit function based on the Fourier-based metric. This metric has been successfully applied in molecular physics for solving the Boltzmann equation, and we adapt it to full-waveform inversion. This misfit function exploits the power spectrum information between the modelled and observed data to provide low-wavenumber velocity model updates early, and more high resolution updates as we approach the solution. Thus, it also can be reformulated as a weighted ℓ2-norm in a quadratic case, which can be seen as a simple extension for conventional full-waveform inversion. Thus, despite its robustness to cycle skipping, it is capable of delivering high-resolution models synonymous to conventional FWI. Considering its frequency domain utilization, we refer to this inversion method as ω-FWI. Through the synthetic Marmousi model example, this method successfully recovers an accurate velocity model, starting from a linearly increasing model even for the case of noisy observed data and the lack of low frequencies below 3 Hz and 5Hz, in which the conventional ℓ2-norm full-waveform inversion suffers from cycle skipping.
    • Adsorption of Polar Species at Crude Oil–Water Interfaces: the Chemoelastic Behavior

      Saad, Ahmed Mohamed; Aime, Stefano; Chandra Mahavadi, Sharath; Song, Yi-Qiao; Yutkin, Maxim; Weitz, David; Patzek, Tadeusz (Langmuir, American Chemical Society (ACS), 2022-05-17) [Article]
      We investigate the formation and properties of crude oil/water interfacial films. The time evolution of interfacial tension suggests the presence of short and long timescale processes reflecting the competition between different populations of surface-active molecules. We measure both the time-dependent shear and extensional interfacial rheology moduli. Late-time interface rheology is dominated by elasticity, which results in visible wrinkles on the crude oil drop surface upon interface disturbance. We also find that the chemical composition of the interfacial films is affected by the composition of the aqueous phase that it has contacted. For example, sulfate ions promote films enriched with carboxylic groups and condensed aromatics. Finally, we perform solution exchange experiments and monitor the late-time film composition upon the exchange. We detect the film composition change upon replacing chloride solutions with sulfate-enriched ones. To the best of our knowledge, we are the first to report the composition alteration of aged crude oil films. This finding might foreshadow an essential crude oil recovery mechanism.
    • Revisiting low temperature oxidation chemistry of n-heptane

      Xie, Cheng; Lailliau, Maxence; Issayev, Gani; Xu, Qiang; Chen, Weiye; Dagaut, Philippe; Farooq, Aamir; Sarathy, Mani; Wei, Lixia; Wang, Zhandong (Combustion and Flame, Elsevier BV, 2022-05-17) [Article]
      Benefitting from the rapid development of instrumental analysis methods, intermediate products that were difficult to probe in the past can now be measured and quantified in complex reaction systems. To understand low temperature reactions of interest for combustion applications, and reduce the deviations between model predictions and experimental measurements, constant advancement in understanding low temperature oxidation process is necessary. This work examines the oxidation of n-heptane in jet-stirred reactors at atmospheric pressure, with an initial n-heptane mole fraction of 0.005, equivalence ratio of 0.5, a residence time of 1s, and over a temperature range of 500-800 K. Reaction products were analyzed using synchrotron ultra-violet photoionization mass spectrometry, gas chromatography, and Fourier-transform infrared spectroscopy. Ignition delay times of n-heptane/O2/CO2 mixture were measured in a rapid compression machine at 20 and 40 bar over a 600-673 K temperature range. Based on the experimental results, a comprehensive kinetic model of n-heptane low temperature oxidation was developed by considering the sub-mechanisms of keto-hydroperoxide, cyclic ether, heptene isomers, and the third O2 addition reaction, and by updating the rate constants of keto-hydroperoxide decomposition and second oxygen addition reactions. The combination of reaction mechanism development and evaluation of the rate constants of key reactions enabled the model to effectively predict the species concentrations and ignition delay times of n-heptane low temperature oxidation, providing additional insight into alkane low temperature oxidation chemistry.
    • Spatio-Temporal Cross-Covariance Functions under the Lagrangian Framework with Multiple Advections

      Salvaña, Mary Lai O.; Lenzi, Amanda; Genton, Marc G. (Journal of the American Statistical Association, Informa UK Limited, 2022-05-17) [Article]
      When analyzing the spatio-temporal dependence in most environmental and earth sciences variables such as pollutant concentrations at different levels of the atmosphere, a special property is observed: the covariances and cross-covariances are stronger in certain directions. This property is attributed to the presence of natural forces, such as wind, which cause the transport and dispersion of these variables. This spatio-temporal dynamics prompted the use of the Lagrangian reference frame alongside any Gaussian spatio-temporal geostatistical model. Under this modeling framework, a whole new class was birthed and was known as the class of spatio-temporal covariance functions under the Lagrangian framework, with several developments already established in the univariate setting, in both stationary and nonstationary formulations, but less so in the multivariate case. Despite the many advances in this modeling approach, efforts have yet to be directed to probing the case for the use of multiple advections, especially when several variables are involved. Accounting for multiple advections would make the Lagrangian framework a more viable approach in modeling realistic multivariate transport scenarios. In this work, we establish a class of Lagrangian spatio-temporal cross-covariance functions with multiple advections, study its properties, and demonstrate its use on a bivariate pollutant dataset of particulate matter in Saudi Arabia.
    • Holey Reduced Graphene Oxide Scaffolded Heterocyclic Aramid Fibers with Enhanced Mechanical Performance

      Li, Jiaqiang; Wen, Yeye; Xiao, Zhihua; Wang, Shijun; Zhong, Lixiang; Li, Tao; Jiao, Kun; Li, Lanying; Luo, Jiajun; Gao, Zhenfei; Li, Shuzhou; Zhang, Zhong; Zhang, Jin (Advanced Functional Materials, Wiley, 2022-05-17) [Article]
      Poly(p-phenylene-benzimidazole-terephthalamide) (PBIA) fibers, a kind of heterocyclic aramid fibers, possess extraordinary mechanical properties and advanced applications in aerospace, military protection, and other civilian areas. However, harsh application scenarios are putting forward even stringent requirements for the mechanical performances and environmental compatibility of PBIA fibers. Strengthening lateral interactions between polymer chains are approachable methods but ongoing challenges to obtain PBIA fibers with high-performance. This work develops a novel holey reduced-graphene-oxide (HrGO)/PBIA composite fiber with a scaffolded structure, in which the HrGO plays a role of clamp to effectively band plentiful PBIA chains through the in-plane holes. A small amount of HrGO (0.075 wt%) is able to improve the tensile strength and Young's modulus of HrGO/PBIA fibers by 11.5% and 8.3%, respectively. The small amount of well dispersed HrGO improves the crystallinity and serves as the topological constraint that enhances the lateral interaction of the PBIA chains, which is unveiled by the wide-angle X-ray scattering and the coarse-grained molecular dynamics simulations. In addition, the favorable compatibility of HrGO/PBIA fibers in complex application scenarios is demonstrated by the dynamic and cyclic-loading measurements.
    • Role of C-Reactive Protein in Diabetic Inflammation

      Stanimirovic, Julijana; Radovanovic, Jelena; Banjac, Katarina; Obradovic, Milan; Essack, Magbubah; Zafirovic, Sonja; Gluvic, Zoran; Gojobori, Takashi; Isenovic, Esma (Mediators of Inflammation, Hindawi Limited, 2022-05-17) [Article]
      Even though type 2 diabetes mellitus (T2DM) represents a worldwide chronic health issue that affects about 462 million people, specific underlying determinants of insulin resistance (IR) and impaired insulin secretion are still unknown. There is growing evidence that chronic subclinical inflammation is a triggering factor in the origin of T2DM. Increased C-reactive protein (CRP) levels have been linked to excess body weight since adipocytes produce tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6), which are pivotal factors for CRP stimulation. Furthermore, it is known that hepatocytes produce relatively low rates of CRP in physiological conditions compared to T2DM patients, in which elevated levels of inflammatory markers are reported, including CRP. CRP also participates in endothelial dysfunction, the production of vasodilators, and vascular remodeling, and increased CRP level is closely associated with vascular system pathology and metabolic syndrome. In addition, insulin-based therapies may alter CRP levels in T2DM. Therefore, determining and clarifying the underlying CRP mechanism of T2DM is imperative for novel preventive and diagnostic procedures. Overall, CRP is one of the possible targets for T2DM progression and understanding the connection between insulin and inflammation may be helpful in clinical treatment and prevention approaches.
    • Rootstock–scion combination contributes to shape diversity and composition of microbial communities associated with grapevine root system

      Marasco, Ramona; Alturkey, Hend; Fusi, Marco; Brandi, Michele; Ghiglieno, Isabella; Valenti, Leonardo; Daffonchio, Daniele (Environmental Microbiology, Wiley, 2022-05-17) [Article]
      To alleviate biotic and abiotic stresses and enhance fruit yield, many crops are cultivated in the form of grafted plants, in which the shoot (scion) and root (rootstock) systems of different species are joined together. Because (i) the plant species determines the microbial recruitment from the soil to the root and (ii) both scion and rootstock impact the physiology, morphology and biochemistry of the grafted plant, it can be expected that their different combinations should affect the recruitment and assembly of plant microbiome. To test our hypothesis, we investigated at a field scale the bacterial and fungal communities associated with the root system of seven grapevine rootstock–scion combinations cultivated across 10 different vineyards. Following the soil type, which resulted in the main determinant of the grapevine root microbial community diversity, the rootstock–scion combination resulted more important than the two components taken alone. Notably, the microbiome differences among the rootstock–scion combinations were mainly dictated by the changes in the relative abundance of microbiome members rather than by their presence/absence. These results reveal that the microbiome of grafted grapevine root systems is largely influenced by the combination of rootstock and scion, which affects the microbial diversity uptaken from soil.
    • Photoactivated p-Doping of Organic Interlayer Enables Efficient Perovskite/Silicon Tandem Solar Cells

      Zheng, Xiaopeng; Liu, Jiang; Liu, Tuo; Aydin, Erkan; Chen, Min; Yan, Wenbo; de Bastiani, Michele; Allen, Thomas; Yuan, Shuai; Kirmani, Ahmad R.; Baustert, Kyle N.; Salvador, Michael; Turedi, Bekir; Alsalloum, Abdullah Yousef; Almasabi, Khulud M.; Kotsovos, Konstantinos; Gereige, Issam; Liao, Liang-Sheng; Luther, Joseph; Graham, Kenneth R.; Mohammed, Omar F.; De Wolf, Stefaan; Bakr, Osman (ACS Energy Letters, American Chemical Society (ACS), 2022-05-17) [Article]
      Solution-processed organic semiconductor layers on rough surfaces tend to vary widely in thickness, significantly hindering charge extraction in relevant optoelectronic devices. Herein, we report the photoactivated p-doping of hole-transporting material (HTM) to enhance hole extraction for (textured) perovskite/silicon tandem solar cells, making the device performance less sensitive to the variation of hole transport layer thickness. We used the ionic compound 4-isopropyl-4′-methyldiphenyliodonium tetrakis(penta-fluorophenyl-borate) (DPI-TPFB) as a p-type dopant in poly(triaryl amine) (PTAA), which we used as the HTM. We observed that light soaking DPI-TPFB-doped PTAA shows approximately 22 times higher conductivity compared with an undoped PTAA film, which translated into an improved fill factor (FF) for tandem solar cells. Our tandem solar cells achieved an ∼80% FF and 27.8% efficiency and operated at their maximum power point for 200 h without loss of performance, in addition to retaining ∼83% of initial performance over a month of operation in an outdoor environment.
    • Charging Techniques for UAV-Assisted Data Collection: Is Laser Power Beaming the Answer?

      Lahmeri, Mohamed-Amine; Kishk, Mustafa A.; Alouini, Mohamed-Slim (IEEE Communications Magazine, Institute of Electrical and Electronics Engineers (IEEE), 2022-05-17) [Article]
      As COVID-19 has increased the need for connectivity around the world, researchers are targeting new technologies that could improve coverage and connect the unconnected in order to make progress toward the United Nations Sustainable Development Goals. In this context, drones are seen as one of the key features of 6G wireless networks that could extend the coverage of previous wireless network generations. That said, limited onboard energy seems to be the main drawback that hinders the use of drones for wireless coverage. Therefore, different wireless and wired charging techniques, such as laser beaming, charging stations, and tether stations, are proposed. In this article, we analyze and compare these different charging techniques by performing extensive simulations for the scenario of drone-assisted data collection from ground-based Internet of Things devices. We analyze the strengths and weaknesses of each charging technique, and finally show that laser-powered drones strongly compete with, and outperform in some scenarios, other charging techniques.
    • Untargeted Metabolomic Profiling and Antioxidant Capacities of Different Solvent Crude Extracts of Ephedra foeminea

      Al-Nemi, Ruba; Makki, Arwa A.; Sawalha, Khaled; Hajjar, Dina A.; Jaremko, Mariusz (Metabolites, MDPI AG, 2022-05-17) [Article]
      Ephedra foeminea is a traditional medicinal plant used in the Eastern Mediterranean region. This study aims to investigate the chemical profiles of different solvent extracts of E. foeminea via an untargeted metabolomics approach, alongside determining their antioxidant capacities. E. foeminea samples collected from Jordan were macerated in solvents of varying polarities; dichloromethane/methanol, methanol, ethanol, ethyl acetate, and acetone. The crude extracts were subjected to comprehensive chemical profiling and metabolomics study using Gas chromatography–Mass spectrometry (GC–MS), Liquid chromatography–Mass spectrometry (LC–MS), and Nuclear Magnetic Resonance (NMR). The obtained data were analyzed using Venn diagrams, Principle Component Analysis (PCA), and Metabolite Enrichment Set Analysis (MESA). ABTS assay was performed to measure the crude extracts’ antioxidant activity. MESA revealed the dominant chemical groups as amino acids, fatty acids, carboxylic acids, and carbohydrates. Results indicated that dichloromethane/methanol and methanolic extracts had the most distinct composition as well as the most unique compounds. The methanolic extract had the most potency (IC50 249.6 µg/mL) in the ABTS assay. However, no significant differences were found. In conclusion, solvents influenced the recovery of metabolites in E. foeminea and the antioxidant activity of the E. foeminea methanolic extract could be correlated to the abundant presence of diverse bioactive compounds.
    • Reconfigurable Intelligent Surface Enabled Interference Nulling and Signal Power Maximization in mmWave bands

      Ye, Jia; Kammoun, Abla; Alouini, Mohamed-Slim (IEEE Transactions on Wireless Communications, Institute of Electrical and Electronics Engineers (IEEE), 2022-05-17) [Article]
      Reconfigurable intelligent surface (RIS) has emerged as a promising mean to enhance wireless transmission. The effective reflected paths provided by RIS are able to alleviate the susceptibility to blockage effects, especially in high-frequency band communications, where signals experience severe path loss and high directivity. This paper is concerned with an RIS-assisted system over the millimeter wave (mmWave) channel characterized by sparse propagation paths. A base station tries to connect with the desired user through an RIS, while the undesired user can also receive the signal transmitted from BS unavoidably, which is treated as the interference signal. All terminals are assumed to be equipped with a single antenna for the sake of simplicity. The paper aims to propose an appropriate design of the phase shifts of each element at the RIS so as to maximize the received signal power transmitted from the base station (BS) at the desired user, while nulling the received interference signal power at the undesired user. The proposed reflecting design relies on the decomposition of the reflecting beamforming vectors and all channel path vectors into Kronecker product of factors being uni-modulus vectors. By exploiting characteristics of Kronecker mixed products, different factors of the reflecting are designed for either nulling the interference signal at the undesired user, or coherently combining data paths at the desired user. Furthermore, a channel estimation strategy is proposed to enable the proposed reflecting beamforming design. The magnitude, azimuth, and elevation arrival and departure angles of desired and undesired paths are estimated by an efficient 2-dimension (2-D) line spectrum optimization technique based on the atomic norm minimization (ANM) framework. The performance of the reflecting designs and channel estimation scheme is analyzed and demonstrated by simulation results.
    • Ergodic Capacity Analysis of UAV-based FSO Links over Foggy Channels

      Jung, Kug-Jin; Nam, Sung Sik; Alouini, Mohamed-Slim; Ko, Young-Chai (IEEE Wireless Communications Letters, Institute of Electrical and Electronics Engineers (IEEE), 2022-05-17) [Article]
      In this paper, we investigate the ergodic capacity of unmanned aerial vehicle (UAV)-based free space optics (FSO) links over random foggy channel. More specifically, we derive composite probability density function (PDF) and close approximation for the moments of the composite PDF using the statistical model of a UAV-based 3D pointing error and a random foggy channel. With it, we obtain upper bound and asymptotic approximation of the ergodic capacity for the two possible detection techniques of intensity modulation/direct detection (IM/DD) and heterodyne detection at high and low signal-to-noise ratio (SNR) regimes. The numerical results confirm all the presented analytic results via computer-based Monte-Carlo simulations.
    • Microstructural analysis of N-polar InGaN directly grown on a ScAlMgO4(0001) substrate

      Velazquez-Rizo, Martin; Najmi, Mohammed A.; Iida, Daisuke; Kirilenko, Pavel; Ohkawa, Kazuhiro (Applied Physics Express, IOP Publishing, 2022-05-17) [Article]
      We report the characterization of a N-polar InGaN layer deposited by metalorganic vapor-phase epitaxy on a ScAlMgO4(0001) (SAM) substrate without a low-temperature buffer layer. The InGaN layer was tensile-strained, and its stoichiometry corresponded to In0.13Ga0.87N. We also present the microstructural observation of the InGaN/SAM interface via integrated differential phase contrast-scanning transmission electron microscopy. The results show that the interface between N-polar InGaN and SAM occurs between the O atoms of the O–Sc SAM surface and the (Ga,In) atoms of InGaN.
    • Deciphering resistance to Zymoseptoria tritici in the Tunisian durum wheat landrace accession 'Agili39'

      Ferjaoui, Sahbi; Aouini, Lamia; Slimane, Rim B; Ammar, Karim; Dreisigacker, Suzanne; Schouten, Henk J; Sapkota, Suraj; Bahri, Bochra A; Ben M'Barek, Sarrah; Visser, Richard G F; Kema, Gert H J; Hamza, Sonia (BMC genomics, Springer Science and Business Media LLC, 2022-05-17) [Article]
      Background: Septoria tritici blotch (STB), caused by Zymoseptoria tritici (Z. tritici), is an important biotic threat to durum wheat in the entire Mediterranean Basin. Although most durum wheat cultivars are susceptible to Z. tritici, research in STB resistance in durum wheat has been limited. Results: In our study, we have identified resistance to a wide array of Z. tritici isolates in the Tunisian durum wheat landrace accession 'Agili39'. Subsequently, a recombinant inbred population was developed and tested under greenhouse conditions at the seedling stage with eight Z. tritici isolates and for five years under field conditions with three Z. tritici isolates. Mapping of quantitative trait loci (QTL) resulted in the identification of two major QTL on chromosome 2B designated as Qstb2B_1 and Qstb2B_2. The Qstb2B_1 QTL was mapped at the seedling and the adult plant stage (highest LOD 33.9, explained variance 61.6%), conferring an effective resistance against five Z. tritici isolates. The Qstb2B_2 conferred adult plant resistance (highest LOD 32.9, explained variance 42%) and has been effective at the field trials against two Z. tritici isolates. The physical positions of the flanking markers linked to Qstb2B_1 and Qstb2B_2 indicate that these two QTL are 5 Mb apart. In addition, we identified two minor QTL on chromosomes 1A (Qstb1A) and chromosome 7A (Qstb7A) (highest LODs 4.6 and 4.0, and explained variances of 16% and 9%, respectively) that were specific to three and one Z. tritici isolates, respectively. All identified QTL were derived from the landrace accession Agili39 that represents a valuable source for STB resistance in durum wheat. Conclusion: This study demonstrates that Z. tritici resistance in the 'Agili39' landrace accession is controlled by two minor and two major QTL acting in an additive mode. We also provide evidence that the broad efficacy of the resistance to STB in 'Agili 39' is due to a natural pyramiding of these QTL. A sustainable use of this Z. tritici resistance source and a positive selection of the linked markers to the identified QTL will greatly support effective breeding for Z. tritici resistance in durum wheat.
    • NMMA: A nuclear-physics and multi-messenger astrophysics framework to analyze binary neutron star mergers

      Pang, Peter T. H.; Dietrich, Tim; Coughlin, Michael W.; Bulla, Mattia; Tews, Ingo; Almualla, Mouza; Barna, Tyler; Kiendrebeogo, Weizmann; Kunert, Nina; Mansingh, Gargi; Reed, Brandon; Sravan, Niharika; Toivonen, Andrew; Antier, Sarah; VandenBerg, Robert O.; Heinzel, Jack; Nedora, Vsevolod; Salehi, Pouyan; Sharma, Ritwik; Somasundaram, Rahul; Broeck, Chris Van Den (arXiv, 2022-05-17) [Preprint]
      The multi-messenger detection of the gravitational-wave signal GW170817, the corresponding kilonova AT2017gfo and the short gamma-ray burst GRB170817A, as well as the observed afterglow has delivered a scientific breakthrough. For an accurate interpretation of all these different messengers, one requires robust theoretical models that describe the emitted gravitational-wave, the electromagnetic emission, and dense matter reliably. In addition, one needs efficient and accurate computational tools to ensure a correct cross-correlation between the models and the observational data. For this purpose, we have developed the NMMA (Nuclear-physics and Multi-Messenger Astrophysics) framework. The code allows incorporation of nuclear-physics constraints at low densities as well as X-ray and radio observations of isolated neutron stars. It also enables us to classify electromagnetic observations, e.g., to distinguish between supernovae and kilonovae. In previous works, the NMMA code has allowed us to constrain the equation of state of supranuclear dense matter, to measure the Hubble constant, and to compare dense-matter physics probed in neutron-star mergers and in heavy-ion collisions. The extension of the NMMA code presented here is the first attempt of analysing the gravitational-wave signal, the kilonovae, and the GRB afterglow simultaneously, which reduces the uncertainty of our constraints. Incorporating all available information, we estimate the radius of a 1.4 solar mass neutron star to be R=11.98+0.35−0.40 km.